"America Idol" fans could be forgiven for feeling a bit of déjà vu on Thursday night when judge Jennifer Lopez performed her song "Dance Again." Just like when she hit the stage this time last year, she was all about the sultry PDA, although her partner had changed.

Instead of shimmying with husband Marc Anthony, J.Lo, 42, got steamy with 25-year-old boyfriend Casper Smart, who has quickly been promoted from her backup dancer to co-star and choreographer.

"He's so cute," she squeaked as Smart pulled confetti from her hair, a "spontaneous" moment that they rehearsed earlier in the week, according to People.

"He treats her like a queen," an insider tells the mag. "She thrives on having a one-on-one relationship where she feels special. Casper centers everything on Jennifer. He watches her, praises her and makes her feel like she is the only woman in the room."

The source then worryingly adds, "It is like he apprenticed from Marc and learned what it takes to get to her. You can see that she loves it."

Not everyone is on board the Smart love train, however.

In Touch claims the hoofer is causing friction within Jennifer's inner circle: "She's letting Casper call all the shots, and that's starting to upset some of her friends," alleges a snitch.

Indeed, a People spy acknowledges that Smart can be "cocky" and "immature." That's not too surprising given that six months ago, he was toiling in obscurity.

Now, he's living in the lap of luxury, shacking up at Lopez's Hidden Hills, Calif., estate with her 4-year-old twins Max and Emme. And when he's not behind the wheel of her Bentley, he's driving the new Dodge Ram truck with monogrammed seats that she gave him for his birthday.

"After her split with Marc, Jennifer was concerned that no one would want to date a 42-year-old mom," reveals a confidant. "She was upset and she felt old and tired. With Casper, she's come alive again."

And with rumors growing louder that Smart will become hubby No. 4, that's a feeling she may be willing to pay for.

"She basically supports him," according to a People source. "The more time they spend together, the more Casper becomes a bigger influence on her life."

And don't be surprised if J.Lo, who recently said another child would be a "blessing," ends up on the stork's delivery route.

"If she could get pregnant with Casper," says a music industry insider, "it would be a happy day for her."